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Hydrate
Kinds of Hydrate Terms modified by Hydrate Selected AbstractsHierachically Nanostructured Mesoporous Spheres of Calcium Silicate Hydrate: Surfactant-Free Sonochemical Synthesis and Drug-Delivery System with Ultrahigh Drug-Loading CapacityADVANCED MATERIALS, Issue 6 2010Jin Wu Ultrahigh drug-loading capacity and the linear relationship between the cumulative amount of released drug and the natural logarithm of release time were discovered for the hierachically nanostructured mesoporous spheres of calcium silicate hydrate (CSH) obtained by a surfactant-free sonochemical method (see figure). During the release of loaded ibuprofen in simulated body fluid, CSH gradually transformed to hydroxyapatite. [source] A Molecular Dynamic Study of Cementitious Calcium Silicate Hydrate (C,S,H) GelsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2007Jorge S. Dolado In this article, we study the polymerization of silicic acids (Si(OH)4) in the presence of calcium ions by molecular dynamics simulations. We focus on the formation and structure of cementitious calcium silicate hydrate (C,S,H) gels. Our simulations confirm that, in accordance with experiments, a larger content of calcium ions slows down the polymerization of the cementitious silicate chains and prevents them from forming rings and three-dimensional structures. Furthermore, by an analysis of the connectivity of our simulated silicate chains and by a count of the number of Ca,OH and Si,OH bonds formed, the relationship with commonly used structural models of C,S,H gels, such as 1.4 nm tobermorite and jennite, is discussed. [source] Hydrogen Gas Sensor Based on Proton-Conducting Clathrate Hydrate,ANGEWANDTE CHEMIE, Issue 46 2009Jong-Ho Cha Eisiger Detektor: Ein neues, einfaches Konzept für den Aufbau amperometrischer H2 -Sensoren beruht auf der Verwendung eines ionischen Clathrathydrats. Die physikochemischen Eigenschaften des Eis-artigen Me4NOH,5,H2O gewährleisten ein schnelles Ansprechen und kurze Erholungszeiten, selbst bei niedrigeren H2 -Konzentrationen. [source] Gas Hydrates in the Qilian Mountain Permafrost, Qinghai, Northwest ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010Youhai ZHU Abstract: Qilian Mountain permafrost, with area about 10×104 km2, locates in the north of Qinghai-Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008,2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK-1, DK-2 and DK-3. Gas hydrate is hosted under permafrost zone in the 133,396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydrate-bearing cores strongly bubble in the water. Gas-bubble and water-drop are emitted from the hydrate-bearing cores and then characteristic of honeycombed structure is left The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal-bed methane origin etc. [source] Theoretical Investigation of the Electronically Excited States of Chlorine HydrateCHEMINFORM, Issue 43 2007Daniel P. Schofield Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Sr(II) in Water: A Labile Hydrate with a Highly Mobile StructureCHEMINFORM, Issue 5 2007Thomas S. Hofer Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Tin-Mediated Reduction of Azoarenes to Hydrazoarenes Using Hydrazine Hydrate.CHEMINFORM, Issue 48 2006B. Dinesh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Convenient Tetrahydropyranylation of Alcohols and Phenols by Catalytic Ferric Sulfate Hydrate (Fe2(SO4)3×xH2O).CHEMINFORM, Issue 14 2006Lingjun Li Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Chemoselective Reaction of Benz(g)indole Based Bisheterocycle Dicarboxylate Towards Hydrazine Hydrate: Synthesis and Antimicrobial Activity of New Triheterocycles-5-pyrrolylaminocarbonyl/mercaptooxadiazolyl/4-allyl-5-me rcaptotriazolylmethoxy-1-furfuryl-2-methylbenz(g)indoles.CHEMINFORM, Issue 45 2005Dundappa S. Donawade Abstract For Abstract see ChemInform Abstract in Full Text. [source] Hydrazine Hydrate Induced Reductive Cleavage of ,,,-Epoxy Ketones: An Efficient Procedure for the Preparation of ,-Hydroxy Ketones.CHEMINFORM, Issue 22 2005Jorge A. R. Salvador Abstract For Abstract see ChemInform Abstract in Full Text. [source] The Use of Trifluoroacetaldehyde Ethyl Hemiacetal or Hydrate in a Simple and Practical Regioselective Synthesis of ,-Hydroxy-,-trifluoromethyl Ketones from Enamines and Imines.CHEMINFORM, Issue 32 2003Kazumasa Funabiki Abstract For Abstract see ChemInform Abstract in Full Text. [source] Hydrogen in Porous Tetrahydrofuran Clathrate HydrateCHEMPHYSCHEM, Issue 9 2008Fokko M. Mulder Dr. Abstract The lack of practical methods for hydrogen storage is still a major bottleneck in the realization of an energy economy based on hydrogen as energy carrier.1 Storage within solid-state clathrate hydrates,2,4 and in the clathrate hydrate of tetrahydrofuran (THF), has been recently reported.5,,6 In the latter case, stabilization by THF is claimed to reduce the operation pressure by several orders of magnitude close to room temperature. Here, we apply in situ neutron diffraction to show that,in contrast to previous reports[5,,6],hydrogen (deuterium) occupies the small cages of the clathrate hydrate only to 30,% (at 274 K and 90.5 bar). Such a D2 load is equivalent to 0.27 wt.,% of stored H2. In addition, we show that a surplus of D2O results in the formation of additional D2O ice Ih instead of in the production of sub-stoichiometric clathrate that is stabilized by loaded hydrogen (as was reported in ref. 6). Structure-refinement studies show that [D8]THF is dynamically disordered, while it fills each of the large cages of [D8]THF,17D2O stoichiometrically. Our results show that the clathrate hydrate takes up hydrogen rapidly at pressures between 60 and 90 bar (at about 270 K). At temperatures above ,220 K, the H-storage characteristics of the clathrate hydrate have similarities with those of surface-adsorption materials, such as nanoporous zeolites and metal,organic frameworks,7,,8 but at lower temperatures, the adsorption rates slow down because of reduced D2 diffusion between the small cages. [source] Reversible Hydrogen Storage in Hydrogel Clathrate HydratesADVANCED MATERIALS, Issue 23 2009Fabing Su The use of inexpensive hydrogels as supports to significantly improve H2 enclathration kinetics and capacities in THF,H2O clathrate hydrate with respect to bulk solutions is demonstrated. Polymer hydrogels give rise to significant rate and capacity enhancements for hydrogen clathrate formation with respect to unmixed bulk systems, suggesting potential for accelerated gas-storage kinetics in clathrate-based technologies. [source] Gas Hydrates in the Qilian Mountain Permafrost, Qinghai, Northwest ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010Youhai ZHU Abstract: Qilian Mountain permafrost, with area about 10×104 km2, locates in the north of Qinghai-Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008,2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK-1, DK-2 and DK-3. Gas hydrate is hosted under permafrost zone in the 133,396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydrate-bearing cores strongly bubble in the water. Gas-bubble and water-drop are emitted from the hydrate-bearing cores and then characteristic of honeycombed structure is left The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal-bed methane origin etc. [source] ChemInform Abstract: Catalytic Activity of Iron(III), Aluminum(III), Cobalt(II), and Magnesium(II) Chloride Crystal Hydrates in the Condensation of Aniline with Butyraldehyde.CHEMINFORM, Issue 9 2010R. G. Bulgakov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Syntheses and Crystal Structures of Rare Earth Basic Nitrates Hydrates.CHEMINFORM, Issue 39 20092 -NO3)6] (NO3)2·xH2O, 3 -OH)8 (H2O)12(, 6 -O)(, Ln: Y, Lu; x = , Part 3. [Ln6( Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: In situ Characterization of Elusive Salt Hydrates , The Crystal Structures of the Heptahydrate and Octahydrate of Sodium Sulfate.CHEMINFORM, Issue 14 2009Iain D. H. Oswald Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Applications of Lanthanide Trichloride Hydrates, Prepared from Mischmetall, in the Biginelli Reaction.CHEMINFORM, Issue 21 2008Marie-Isabelle Lannou Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Crystal Structures of Tin(IV) Chloride Hydrates.CHEMINFORM, Issue 52 2005Sergey N. Semenov Abstract For Abstract see ChemInform Abstract in Full Text. [source] The Crystal Structures of the Dicesium Dodecahalogeno-closo-Dodecaborates Cs2[B12X12] (X: Cl, Br, I) and Their Hydrates.CHEMINFORM, Issue 49 2004Ioannis Tiritiris Abstract For Abstract see ChemInform Abstract in Full Text. [source] Structural Characterization of MII Guanidinium Sulfate Hydrates (MII: Mn, Fe, Co, Ni, Cd, VO).CHEMINFORM, Issue 30 2004Michel Fleck Abstract For Abstract see ChemInform Abstract in Full Text. [source] Hydration of Lanthanoid(III) Ions in Aqueous Solution and Crystalline Hydrates Studied by EXAFS Spectroscopy and Crystallography: The Myth of the "Gadolinium Break"CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2008Ingmar Persson Prof. Abstract The structures of the hydrated lanthanoid(III) ions including lanthanum(III) have been characterized in aqueous solution and in the solid trifluoromethanesulfonate salts by extended X-ray absorption fine structure (EXAFS) spectroscopy. At ambient temperature the water oxygen atoms appear as a tricapped trigonal prism around the lanthanoid(III) ions in the solid nonaaqualanthanoid(III) trifluoromethanesulfonates. Water deficiency in the capping positions for the smallest ions starts at Ho and increases with increasing atomic number in the [Ln(H2O)9,x](CF3SO3)3 compounds with x=0.8 at Lu. The crystal structures of [Ho(H2O)8.91](CF3SO3)3 and [Lu(H2O)8.2](CF3SO3)3 were re-determined by X-ray crystallography at room temperature, and the latter also at 100,K after a phase-transition at about 190,K. The very similar Ln K- and L3 -edge EXAFS spectra of each solid compound and its aqueous solution indicate indistinguishable structures of the hydrated lanthanoid(III) ions in aqueous solution and in the hydrated trifluoromethanesulfonate salt. The mean LnO bond lengths obtained from the EXAFS spectra for the largest ions, La,Nd, agree with estimates from the tabulated ionic radii for ninefold coordination but become shorter than expected starting at samarium. The deviation increases gradually with increasing atomic number, reaches the mean LnO bond length expected for eightfold coordination at Ho, and increases further for the smallest lanthanoid(III) ions, Er,Lu, which have an increasing water deficit. The low-temperature crystal structure of [Lu(H2O)8.2](CF3SO3)3 shows one strongly bound capping water molecule (LuO 2.395(4),Å) and two more distant capping sites corresponding to LuO at 2.56(1),Å, with occupancy factors of 0.58(1) and 0.59(1). There is no indication of a sudden change in hydration number, as proposed in the "gadolinium break" hypothesis. [source] Physicochemical Properties of Ionic Clathrate HydratesCHEMISTRY - AN ASIAN JOURNAL, Issue 1 2010Kyuchul Shin Abstract Ionic clathrate hydrates are known to be formed by the enclathration of hydrophobic cations or anions into confined cages and the incorporation of counterions into the water framework. As the ionic clathrate hydrates are considered for their potential applicability in various fields, including those that involve solid electrolytes, gas separation, and gas storage, numerous studies of the ionic clathrate hydrates have been reported. This review concentrates on the physicochemical properties of the ionic clathrate hydrates and the notable characteristics of these materials regarding their potential application are addressed. [source] Rapid crystal growth without inherent supersaturation induced by nanoscale fluid flows?CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2006M. J. Jones Abstract Crystal growth is a process that only takes place under non-equilibrium conditions and a necessary prerequisite is that the crystal is exposed to a phase that is supersaturated in the material the crystal is composed of, be it a solution, a vapour or a supercooled melt. In industrial mass crystallization the growth rate for a population of crystals (in suspension growth processes [1]) rarely exceeds mean linear velocities of 10 -7 ms -1. Here we present a mass crystallization process which is accompanied by rapid crystal growth several orders of magnitude faster and into a region of solution that is without inherent supersaturation. The material investigated is a solid hydrate that exhibits a solution mediated phase transition to its anhydrous form in the presence of methanol [2]. The phase transition is initiated simply by placing an amount of hydrate crystals into the solvent and is characterized by the rapid emergence of needle-shaped crystals. The needles emanate from the crystal faces of the hydrate crystals and grow into the solution, which is nominally free of the substance to be crystallized. The high growth rate of the crystals, which of the order of up to 10 -4 ms -1 is surprising. Although rapid needle growth has been observed before [3-9], to date a satisfactory explanation for needles growing under the abovementioned conditions is still outstanding. Based upon the topology of the crystals we propose a tentative mechanism for this phenomenon capable of explaining the unusually rapid growth and highlight those questions that need addressing in order to verify this mechanism. X-ray powder diffraction is used to characterize the crystal phase of the needles; confocal fluorescence microscopy reveals that the needles are hollow. The width of these needles is between 0.5 and 5 ,m, their length appears to be limited only by the amount of hydrate available for their formation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Solid State Electrochemical Oxidation Mechanisms Of Morin in Aqueous MediaELECTROANALYSIS, Issue 9 2005Patricia Janeiro Abstract The mechanism of electrochemical oxidation of morin has been studied using cyclic, differential pulse and square-wave voltammetry techniques in aqueous electrolyte with solid, insoluble morin hydrate mechanically transferred to a glassy carbon electrode surface, over a wide pH range. The oxidation mechanism proceeds in sequential steps, related with the hydroxyl groups in the three aromatic rings and the oxidation is pH dependent over part of the pH range the oxidation potentials are shifted to lower values with increasing pH. Oxidation of the 2,,4,dihydroxy moiety at the B ring of morin occurs first, at very low positive potentials, and is a one electron one proton reversible reaction. The hydroxyl groups oxidized at more positive potentials were shown to undergo an irreversible oxidation reaction. [source] Determination of the chiral and achiral related substances of methotrexate by cyclodextrin-modified micellar electrokinetic chromatographyELECTROPHORESIS, Issue 16 2004Roberto Gotti Abstract A cyclodextrin-modified micellar electrokinetic chromatographic (CD-MEKC) method for the determination of the most important potential impurities of methotrexate (MTX): 2,4-diamino-6-(hydroxymethyl)pteridine, aminopterine hydrate, 4-[N -(2-amino-4-hydroxy-6-pteridinylmethyl)- N -methylamino] benzoic acid, 4-[N -(2,4-diamino-6-pteridinylmethyl)- N -methylamino] benzoic acid, and the distomer D -MTX is presented. The MEKC separation of these compounds was optimized by applying a step-by-step approach. The addition of ,-CD to a conventional MEKC system, based on sodium dodecyl sulfate (SDS) as surfactant, showed to be essential for the enantioresolution of racemic MTX as well as for the separation of the achiral impurities. To achieve high-resolution factor between the peaks adjacent to the main component (L -MTX), as required in the analysis of related impurities, the separation conditions were stressed; in particular, the addition of methanol to the CD-MEKC system resulted in a very effective choice. Under the optimized final conditions (100 mM SDS and 45 mM ,-CD in a mixture of 50 mM borate buffer, pH 9.30-methanol (75:25 v/v)), the method was validated showing a general adequate accuracy (93,106% recovery) in the determination of L -MTX related substances at the impurity level of 0.12% w/w with a relative standard deviation (RSD)% lower than 8% (n = 4). The method was successfully applied to the analysis of pharmaceuticals (tablets and injections) which showed to contain the distomer D -MTX as major impurity and aminopterine hydrate as a further related substance in the commercial tablets. [source] Characteristic improvement of metal-contaminated sludge using mineralization technologyENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2010Shao-Hua Hu Abstract This study focuses on improving crystalline characteristics of metal-contaminated sludge. The mineralization behavior of Cu/Al or Cu/Fe coexisting in solution is surveyed, and the characteristics of residue and suspension settling are discussed in the context of water content of residue and settling/specific filtration resistance of suspensions. Experimental data show that the hydrate of Cu4SO4(OH)6 forms during mineralization of copper sulfate solution when hydroxide ion concentration, reaction time, and temperature are not controlled appropriately. Mineral characteristics of the residue are usually poor when the Cu4SO4(OH)6 forms in Cu/Al or Cu/Fe solution. However, Cu4SO4(OH)6 can be further transformed into CuO with wet oxidation or ferrite method, respectively (i.e., mineralization treatment). Water reduction of the residue is from 96.8% to 72.8% in the Cu/Al case or 95.6% to 66.6% in the Cu/Fe case, and the mineralized residue volume is only 1/10 of the hydrate sediment. This is particularly beneficial for sludge disposal. © 2009 American Institute of Chemical Engineers Environ Prog, 2010 [source] Ruthenium ,6 -Hexamethylbenzene Complexes Containing Dichalcogenoimidodiphosphinate LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2009Wai-Man Cheung Abstract Treatment of [Ru(,6 -C6Me6)Cl2]2 with AgOTf (OTf, = triflato) followed by K[N(R2PQ)2] gave the 16-electron complexes [Ru(,6 -C6Me6){,2 -N(R2PQ)2}][OTf] [Q = S, R = Ph (1) or iPr (2); Q = Se, R = Ph (3) or iPr (4)] which were isolated as air-stable blue or dark green crystals. For complex 1, when the crude product was recrystallised from CH2Cl2/hexane in air, orange crystals of [Ru(,6 -C6Me6){,3 -N(Ph2PS)2}][OTf] (1a) were isolated as a minor product. The reaction of compound 1 with ammonia, hydrazine hydrate and 4,4,-bipyridyl(4,4,-bpy) gave the 18-electron adducts [Ru(,6 -C6Me6){,2 -N(Ph2PS)2}L][OTf] [L = NH3 (5), N2H4 (6)] and dinuclear[{Ru(,6 -C6Me6)[,2 -N(Ph2PS)2]}2(,-4,4,-bpy)][OTf]2 (7), respectively. Treatment of compound 2 with Li[BEt3H] and NaBH4 afforded the ethyl [Ru(,6 -C6Me6){N(iPr2PS)2}Et] (8) andhydride [Ru(,6 -C6Me6){,2 -N(iPr2PS)2}H] (9) compounds, respectively. Formal potentials for Ru[N(R2PQ)2] complexes have been determined. The structures for complexes 1, 1a, 5, 6, 8 and 9 have been established by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Microwave-Assisted Hydrothermal Synthesis of Structurally and Morphologically Controlled Sodium Niobates by Using Niobic Acid as a PrecursorEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2008Amauri J. Paula Abstract There are many advantages to using a microwave as a source of heat in hydrothermal reactions. Because it is a quick and homogeneous way to crystallize ceramic powders, it was used in this work for the production of antiferroelectric sodium niobate (NaNbO3) in a cubic-like form and its intermediary phase, disodium diniobate hydrate (Na2Nb2O6.H2O), with a fiber morphology. The syntheses were carried out by treating niobic acid (Nb2O5·nH2O) with NaOH. By changing the reaction time and the concentration of the reactants, particles with different structures and different morphologies could be obtained. The structural evolution of the products of this reaction was elucidated on the basis of the arrangement of the NbO6 octahedral units. Conclusive results were obtained with morphological and structural characterizations through XRD, TEM, MEV, and NMR and Raman spectroscopy. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] endo and exo Coordination of Indanol: Synthesis, Isolation and Structural Characterisation of [H3Ru3(endo -Indanol)(C6Me6)2(O)]+ and [H3Ru3(exo -Indanol)(C6Me6)2(O)]+ as Their Tetrafluoroborate SaltsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2004Ludovic Vieille-Petit Abstract The reaction of 2,3,4,7-tetrahydro-1H -inden-2-ol with ruthenium chloride hydrate in refluxing ethanol yields the chloro-bridged dinuclear complex [RuCl2(indanol)]2 (1). The mononuclear complex [Ru(indanol)(H2O)3]2+ (2), formed in situ from 1 in aqueous solution, reacts with the dinuclear complex [H3Ru2(C6Me6)2]+ to give a trinuclear arene-ruthenium cluster as a mixture of two isomers, the cations [H3Ru3(endo -indanol)(C6Me6)2(O)]+ (3a) and [H3Ru3(exo -indanol)(C6Me6)2(O)]+ (3b), in a 1:1 ratio. The hydroxy function of the indanol ligand is oriented towards the ,3 -oxo cap of 3a, whereas the OH group is bent away from the metal skeleton of 3b. These two isomers, which can easily be separated by silica-gel chromatography, were isolated and characterised as their tetrafluoroborate salts. The single-crystal X-ray structure analysis of [3a][BF4] shows a strong intramolecular hydrogen bond between the ,3 -oxo ligand and the hydroxyl function, which even persists in acetone solution, as demonstrated by NMR spectroscopy. On the other hand, the hydroxy function of 3b was found to be free in the solid state as well as in solution, as shown by an X-ray crystal structure analysis and by NMR spectroscopy. The catalytic activities of the water-soluble trinuclear cations 3a and 3b for the hydrogenation of benzene to give cyclohexane under biphasic conditions are considerably different, the exo isomer 3b being more active than the endo isomer 3a. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||